Since early March, the water of the Bassac River in Kandal’s Sa’ang district has been turning black for days at a time, residents say, decimating local fish farms and leading to an inspection of three nearby factories on Wednesday by local authorities.

“The water would turn black and the fish would die,” said Tiet Saly, 38, a fish farmer in the predominantly Cham village of Boren Krom in Svay Brateal commune.

Saly began the season with 2,500 fish in his cages. At first, just a few died or grew ill, when they stopped eating and growing. But as more died – at one point 50 or 60 at once – he decided to cut his losses months before the usual selling period in July.

“I sold off the rest of my fish, but some families lost hundreds of fish,” he said.

Pheam Yousef, 38, was one of the less fortunate of the 20 or so fish farming families in the village.

Of his stock of 4,000 local catfish and Spanish tilapia, he lost about half, with deaths spiking last week, at which point villagers voiced their grievances with local authorities.

District Governor Nhem Vandin said that fisheries officials and commune authorities carried out inspections on Wednesday morning, but he has yet to receive a report on their findings.

Kan Penh, the district Fisheries Administration chief, said all five points where wastewater was flowing into the river were inspected. It was found that local communal drainage pipes were being used by three factories as well as local villagers, with untreated wastewater going into the river.

“For the factories we ordered them to change their sewage discharge and they promised to correct the problem,” he said.

Officials declined to name the factories in question but The Post identified one as the Taiwanese-owned He Gia Yuan Co Ltd garment factory. A representative hung up on reporters on Wednesday.

In Sitbou commune, across the river, commune authorities say that storm drainage pipes had been “pirated” by local residents, who connected their sewage to them, according to Commune Chief Um Leng.

“I call upon people to make septic tanks, and when they are full, call the sewage trucks to pump it out,” he said. “People need to change their behaviour. I don’t think they understand about the polluted environment.”

Yousef and the other families affected are hopeful the inspection will curb the pollution and possibly secure compensation for farmers.

“I lost 4 million riel [about $1,000] of fish . . . I hope it will be better and the factories keep their promise,” he said.